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/**
******************************************************************************
* File Name : ring_buffer.c
* Description : utility to provide ring buffer component
******************************************************************************
* @attention
*
* <h2><center>© Copyright (c) 2020 STMicroelectronics.
* All rights reserved.</center></h2>
*
* This software component is licensed by ST under Ultimate Liberty license
* SLA0044, the "License"; You may not use this file except in compliance with
* the License. You may obtain a copy of the License at:
* www.st.com/SLA0044
*
******************************************************************************
*/
/* "SPECIFICATIONS"
- support any type as an element (with any size): not for now, only char
- no dynamic allocation
- buffer size can be changed by user
- support adding multiple elements (string)
- support removing multiple elements (string?)
*/
/* Includes ------------------------------------------------------------------*/
#include "app_conf.h"
#include "app_common.h"
#include "dbg_trace.h"
#include "stm_logging.h"
#include "ring_buffer.h"
/* Private includes ----------------------------------------------------------*/
/* Private typedef -----------------------------------------------------------*/
/* Private defines -----------------------------------------------------------*/
/* Private macros ------------------------------------------------------------*/
/* Private function prototypes -----------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
/* Functions Definition ------------------------------------------------------*/
// WARNING: be careful to protect a buffer operation by critical section if it
// can be accessed in interruption too
// Private function to move an index one step forward
static inline void bufIncIndex(const Buffer *buf, uint32_t *index){
*index = (*index + 1) % buf->mem_size;
}
// Initialize buffer structure, must be called first (see BUF_ALLOC)
void bufInit(Buffer *buf, uint32_t size){
buf->idx_rd = 0;
buf->idx_wr = 0;
buf->mem_size = size;
buf->data_size = 0;
}
// Test if buffer is empty
bool bufIsEmpty(const Buffer *buf){
return (0 == buf->data_size);
}
// Test if buffer is full
bool bufIsFull(const Buffer *buf){
return (buf->mem_size == buf->data_size);
}
// Store one byte in buffer
// Call ignored if buffer already full
void bufPutChar(Buffer *buf, char character){
if(! bufIsFull(buf)){
buf->memory[buf->idx_wr] = character;
bufIncIndex(buf, &(buf->idx_wr));
(buf->data_size)++;
}
}
// Store a string in buffer (without '\0')
// When buffer is full, remaining bytes are dropped
void bufPutString(Buffer *buf, const char *string){
uint32_t freeSize = buf->mem_size - buf->data_size;
uint32_t addSize = MIN(strlen(string), freeSize);
uint32_t toEndSize = buf->mem_size - buf->idx_wr;
uint32_t cp1Size = addSize;
uint32_t cp2Size = 0;
if (addSize > toEndSize){
cp1Size = toEndSize;
cp2Size = addSize - toEndSize;
}
memcpy(&(buf->memory[buf->idx_wr]), string, cp1Size);
if (cp2Size == 0){
buf->idx_wr = (buf->idx_wr + cp1Size) % buf->mem_size;
}else{
memcpy(&(buf->memory[0]), &(string[cp1Size]), cp2Size);
buf->idx_wr = cp2Size;
}
buf->data_size += addSize;
}
// Retrieve one byte from buffer
// Buffer must not be empty (check with bufIsEmpty())
char bufGetChar(Buffer *buf){
char character;
character = buf->memory[buf->idx_rd];
bufIncIndex(buf, &(buf->idx_rd));
(buf->data_size)--;
return character;
}
// Retrieve at most size chars from buffer, return actual count copied
uint32_t bufGetMultiChar(Buffer *buf, char *dest, uint32_t size){
uint32_t count = 0;
while (! bufIsEmpty(buf) && (count < size)){
*dest = bufGetChar(buf);
dest++;
count++;
}
return count;
}
#define TEST(EXP) \
do { \
if(!(EXP)) { \
PRINT_MESG_DBG("Test failed on line %d: " #EXP, __LINE__); \
all_passed = false; \
} \
} while (0)
#define BUF_TEST_SIZE 128
// Test buffer code
void bufTest(void){
uint32_t i;
bool all_passed = true;
char bufMem[sizeof(Buffer) + BUF_TEST_SIZE];
Buffer *buf = (Buffer *)&bufMem;
PRINT_MESG_DBG("entering %s()", __func__);
bufInit(buf, BUF_TEST_SIZE);
TEST(bufIsEmpty(buf));
bufPutChar(buf, 'a');
TEST(!bufIsEmpty(buf));
TEST(!bufIsFull(buf));
TEST('a' == bufGetChar(buf));
TEST(bufIsEmpty(buf));
TEST(bufIsEmpty(buf));
const char testString[] = "ST Microelectronics";
char checkString[64];
i = 0;
bufPutString(buf, testString);
while(!bufIsEmpty(buf)){
checkString[i] = bufGetChar(buf);
i++;
}
checkString[i] = '\0';
TEST(0 == strcmp(testString, checkString));
for(uint32_t i = 0; i<buf->mem_size; i++){
bufPutChar(buf, 'a');
}
TEST(!bufIsEmpty(buf));
TEST(bufIsFull(buf));
// Check that new entries are ignored when full
bufPutChar(buf, 'b');
i = 0;
while(!bufIsEmpty(buf)){
TEST('a' == bufGetChar(buf));
i++;
}
TEST(buf->mem_size == i);
// Check interleaved access
TEST(bufIsEmpty(buf));
bufPutChar(buf, 'a');
bufPutChar(buf, 'b');
TEST('a' == bufGetChar(buf));
bufPutChar(buf, 'c');
TEST('b' == bufGetChar(buf));
TEST('c' == bufGetChar(buf));
TEST(bufIsEmpty(buf));
// Check bufPutString without rollover
bufInit(buf, BUF_TEST_SIZE);
const char testString2[] = "ring buffer test string";
bufPutString(buf, testString2);
i = 0;
while(!bufIsEmpty(buf)){
checkString[i] = bufGetChar(buf);
i++;
}
checkString[i] = '\0';
TEST(0 == strcmp(testString2, checkString));
// Check bufPutString with rollover
bufInit(buf, BUF_TEST_SIZE);
const char testString3[] = "ring buffer rollover test string";
for (i=0; i < (BUF_TEST_SIZE - 10); i++){
bufPutChar(buf, 'm');
}
for (i=0; i < 30; i++){
bufGetChar(buf);
}
bufPutString(buf, testString3);
for (i=0; i < (BUF_TEST_SIZE -10 -30); i++){
bufGetChar(buf);
}
i = 0;
while(!bufIsEmpty(buf)){
checkString[i] = bufGetChar(buf);
i++;
}
checkString[i] = '\0';
PRINT_MESG_DBG(checkString);
TEST(0 == strcmp(testString3, checkString));
if(all_passed){
PRINT_MESG_DBG("Ring buffer: all tests passed");
}
}
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
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